Fix pre/post strategy for modifier coverage

[cgewecke]

PR fixes two problems discovered running dForceLending

• Modifier branches were not isolated from reverts downstream from them, resulting in false branch hits. New strategy is to have the post-condition as its own modifier, instead of positioning it after the _;
• Matrix is not being generated correctly when only line coverage is enabled. Not certain what's going wrong here, just disabled the disabling for now since there's no obvious slowdown on a project that size.

[codecov-io]

Codecov Report

Merging #595 (d79dfa6) into experimental-options (7a5b10f) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@                   Coverage Diff                    @@
##           experimental-options     #595      +/-   ##
========================================================
- Coverage                 99.12%   99.11%   -0.02%     
========================================================
  Files                        22       22              
  Lines                      1146     1133      -13     
========================================================
- Hits                       1136     1123      -13     
  Misses                       10       10              

Impacted Files	Coverage Δ
plugins/resources/plugin.utils.js	97.64% <ø> (-0.14%)	⬇️
lib/injector.js	100.00% <100.00%> (ø)
lib/registrar.js	100.00% <100.00%> (ø)

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